22:1/2*2

88

Explanation: Treat ":" as division. With left-to-right evaluation for ÷ and ×: 22 ÷ (1/2) × 2 = (22 ÷ 1/2) × 2 = 44 × 2 = 88

Note: If it were interpreted as 22 ÷ (1/2 × 2) that would be 22 ÷ 1 = 22. The standard rule is left-to-right for ÷ and ×.